1. Field of the Invention
The present invention relates to a substrate processing apparatus and a method in which a plurality of substrates are continuously transported among substrate processing parts and efficiently processed. The substrates are classified in different types of lots so as to be transported to the substrate processing parts in different orders and processed with different control parameters, i.e., control conditions of the substrate processing parts, and the like.
2. Description of the Background Art
As well known, in a substrate processing apparatus used to manufacture a pprecision electronic board such as a liquid crystal display board and a semiconductor substrate (hereinafter simply "substrate"), a substrate held by substrate transport means such as a substrate transport robot is transported in a predetermined order among substrate processing parts disposed in an appropriate arrangement such as a rotary spin coating part (hereinafter "spin coater"), a rotary developing part (hereinafter "spin developer"), an adhesive agent coating unit, a cooling plate, a hot plate and etc., while loaded into and unloaded from these processing parts so that the substrate is processed in a continuous series of treatments. As herein termed, "substrate processing parts" generally refer to a spin coater, a spin developer and etc. When referred to individually, a spin coater, a spin developer and the like are referred to by their respective names.
When the substrate processing apparatus successively processes lots which are to be transported in the same flow (i.e.,, a transportation order to the respective substrate processing parts) but in accordance with different data such as a heating time, the last substrate in a preceding or precedent lot and the first substrate in a subsequent lot are loaded into the substrate processing parts successively without any delay. To successively load these substrates without any delay, while the first substrate in the subsequent lot which is loaded during a transitional period is transported at delayed timing or a tact time of the subsequent lot coincides with a tact time of the precedent lot (Japanese Patent Laid-Open Gazette No. 4-113612). As a result, the substrates are processed successively, whereby the through put is improved. Furthermore, the substrates stored in the same lot are prevented from having different heat histories.
If flows for lots which are to be transported are substantially different from each other (e.g., some flows include heating process and spin coating and some other flows do not), interference between, i.e., confusion of treatments on substrates of a precedent lot and a subsequent lot is created due to contention between these substrates or passing of one substrate. To overcome this problem, in the substrate processing apparatus, processing of the substrates of the subsequent lot is stared after all of the processed substrates of the precedent lot are returned into a cassette. Hence, many substrate processing parts stay idle during a transition between the precedent and the subsequent lots which have different flows from each other. The loss time created at this stage substantially deteriorates the through put. When there is no substrate processing part which processes both the precedent and the subsequent lots, in particular, all substrate processing parts which are necessary to process the subsequent lot cannot be used while the precedent lot is processed, resulting in a decrease in efficiency.